Color resistance dispersion liquid and application

Abstract

The invention relates to the field of display panel preparation, in particular to color resistance dispersion liquid and application. Dispersion resin modified on the surfaces of pigment particles has charged groups and polymeric groups, and a polymerization technology and a charged selective electrophoretic deposition (SEPD) technology are combined to manufacture the full-color CF substrate, so that the purposes of high reliability, process saving, cost reduction and environmental protection are achieved.

Description

Technical Field

[0001] The present invention relates to the field of display panel preparation, and in particular to a color resist dispersion liquid and applications thereof. Background Art

[0002] The full-color CF substrate is used as the upper substrate of the TFT-LCD panel. It is combined with the TFT substrate to form a liquid crystal box. The backlight white light is decomposed into three primary colors of red, green and blue through the light filtering principle to achieve full-color display. The preparation process of the full-color CF substrate generally includes the following steps: 1. Substrate processing High-purity glass is used as the substrate, and cleaning and surface activation treatment are carried out to ensure the uniformity and adhesion of the subsequent coating.

[0003] 2 Black Matrix (BM) Formation A carbon black-containing photoresist is applied, and a grid-like shading structure is formed through exposure and development processes to separate pixels and improve contrast.

[0004] 3 color layers (R / G / B color resist) coating The red, green and blue color resist materials (such as acrylic resin-based photoresist) are sequentially coated by pigment dispersion or dyeing, and a precise pixel array is formed by photolithography. The color resist material must meet the requirements of high color purity, heat resistance and chemical stability.

[0005] 4 Over Coat Apply a transparent resin layer (such as acrylic, silicone resin, or polyimide) to flatten the surface, protect the color resist layer, and enhance mechanical strength.

[0006] However, due to the diffraction of UV light during the exposure process of the LCD CF film mask, the line width and precision of the color resist are often limited. The resolution of conventional CF exposure machines is at least ~10μm, which is difficult to meet the needs of high-resolution products such as AR / VR. Therefore, the current manufacturing of high-PPI color resist layers is generally achieved by developing high-standard color resist + high-resolution exposure machines, which makes its manufacturing cost relatively high.

[0007] Charged selective electrophoretic deposition (SEPD) technology has shown potential in the preparation of colloidal quantum dot (QD) displays. Using photolithography combined with SEPD technology, quantum dot patterns are selectively deposited only on patterned electrodes, achieving uniform, rapid, and low-cost QD pattern manufacturing over large areas of more than 1,000 pixels per inch. However, colloidal quantum dots deposited in this way are only physically deposited to form a film, which is prone to film peeling and has poor reliability. Summary of the invention

[0008] In view of the above shortcomings such as the difficulty and high cost in preparing a high PPI color resist layer, the present invention provides a color resist dispersion and its application.

[0009] Provide a reliable photosensitive electrodeposition material solution to solve the curing process problem of the later stage of the electrodeposition material and improve the optical performance and reliability of the color resist layer.

[0010] The technical solution of the present invention is achieved by the following method: providing a color resist dispersion liquid, comprising a polar solvent, a monomer dissolved in the polar solvent, and a modified pigment; The modified pigment is a pigment whose surface is modified and connected to a dispersing resin, wherein the dispersing resin has a charged group and a polymerizing group; the charged group dissociates and becomes charged in the polar solvent, and the polymerizing group and the monomer can undergo a cross-linking polymerization reaction under initiation conditions.

[0011] In a preferred embodiment of the present invention, the polar solvent is selected from one of diethylene glycol dimethyl ether, diethylene glycol diethyl ether, ethylene glycol dibutyl ether, ethylene glycol ethyl ether acetate, diethylene glycol ethyl ether acetate, diethylene glycol butyl ether acetate, propylene glycol monomethyl ether ester (PGMEA), cyclohexanone, and isophorone; The charged group is selected from at least one of -OH, -COOH, -NH2, and -NHR.

[0012] In a preferred embodiment of the present invention, the initiation condition is photoinitiation, and the photosensitive reaction group on the polymerizing group reacts with the monomer to undergo a photocuring reaction. The photosensitive group of the photoresist must be a monomer containing an unsaturated group (alkenyl, alkynyl) so that the deposited pigments (polymers) are cross-linked and cured. According to the exposure light source and radiation source, it is divided into ultraviolet photoresist (including ultraviolet positive and negative photoresist), deep ultraviolet photoresist, X-ray glue, electron beam glue, ion beam glue, etc.

[0013] In a preferred embodiment of the present invention, the initiation condition is thermal initiation, and the thermosensitive reactive group on the polymerizable group undergoes a thermal curing reaction with the monomer.

[0014] In a preferred embodiment of the present invention, the heat-sensitive reactive group is a silicon-oxygen bond in a silicon-oxygen chain, and the silicon-oxygen bond can react with a silane monomer to undergo an organic silicon thermal polymerization reaction under heat-initiated conditions.

[0015] In a preferred embodiment of the present invention, the heat-sensitive reactive group is an epoxy group, which can undergo epoxy thermal polymerization reaction with the monomer under thermal initiation conditions.

[0016] The present invention also provides a method for preparing a color resist layer, comprising the following steps: S1, the entire surface of R, G, and B electrodes are carved on the CF substrate using photolithography technology; S2. The aforementioned color resist dispersion is electrically controlled to make the modified pigment be directionally deposited on the three electrodes; a polymer material (dispersion resin) containing a charged group and a polymerization group is directly grafted onto the R, G, and B pigment molecules, so that the pigment particles have a single charge and are evenly dispersed in the solvent, thereby obtaining a corresponding color resist dispersion; S3. Under initiation conditions, the polymeric groups on the modified pigment undergo cross-linking polymerization with the monomers, and cross-linking and curing form a color resist layer.

[0017] In a preferred embodiment of the present invention, the electrodes of each color are connected to facilitate the later power-on. The required R, G, and B electrode shapes are engraved on the substrate, which can be circular, square, rectangular, etc. (the shape can be adjusted at will according to the needs of the machine model), which will determine the final shape of the color resist layer after electrophoretic deposition.

[0018] In a preferred embodiment of the present invention, color resist dispersions of three colors, R, G, and B, are used one by one to form color resist layers of corresponding colors respectively.

[0019] In a preferred embodiment of the present invention, after curing one color of color resist, it is cleaned and then another color resist process is performed. The area without pigment cannot be cross-linked and cured because there is no pigment, and no color resist residue will be generated.

[0020] The beneficial effects are as follows: The full-color CF substrate is produced by combining the initiated polymerization technology with the pigment charged selective electrophoretic deposition (SEPD), achieving the goals of high reliability, saving process, reducing cost, and being green and environmentally friendly.

[0021] (1) High reliability. Different from the traditional one-step curing (two electrodepositions followed by whole-surface curing), this patent adopts curing one by one (electrodeposition R→curing R→cleaning→electrodeposition G→…), curing one color resist before proceeding to other color resist processes, effectively avoiding color mixing between different color resists.

[0022] (2) High resolution. By modifying the pigment molecules with charges and grafting polymer groups, the pigment particles can be precisely deposited on the electrode after power is applied, with a minimum resolution of 2 μm.

[0023] (3) Simple process. After the pigment is deposited, the entire surface is cured. Its polymer groups can polymerize with the free monomers in the solvent to solidify the pigment molecules. The positions without pigment can be directly released through a cleaning process.

[0024] (4) Good optical properties. The pre-grafted polymer can ensure the uniform dispersion of the pigment in the color resist layer, thus making the light output more uniform.

[0025] (5) Eliminating the BM process and improving the penetration rate. After different pigments are accurately deposited on their respective electrodes, there is no longer any overlap between the film layers, so the BM between the overlaps can be omitted, which can also improve the panel penetration rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG. 1( a ) is a schematic diagram of the process of modifying the reaction site of the pigment in Example 1, and FIG. 1( b ) is a schematic diagram of the process of modifying the pigment in Example 1 to connect the dispersed resin.

[0027] FIG. 2( a ) is a schematic diagram of the process of modifying the reaction site of the pigment in Example 2, and FIG. 2( b ) is a schematic diagram of the process of modifying the pigment in Example 2 to connect the dispersed resin.

[0028] Figure 3 It is the infrared spectrum of the modified R and G pigments in the embodiment.

[0029] Figure 4 Schematic diagram of the structure of the three electrodes R, G, and B on the substrate. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0032] Option 1: The photosensitive polymer (resin) is modified on the surface of the pigment particles. The -COOH (or -NH2) and other groups on the polymer can be dissociated in polar solvents and charged. Then, the pigment is selectively deposited by applying electricity, so that the pigment can be deposited at the corresponding position. The photosensitive reaction groups on the polymer can provide cross-linking sites for subsequent photocuring.

[0033] The key to this invention is pigment modification, and the specific steps are: (1) Modify the active groups on the surface of R, G, and B pigment molecules to provide reaction sites for subsequent polymer coating, which can be further reactive groups such as -OH, vinyl, acetylene, halogen, etc.

[0034] (2) Coating the surface of the pigment particles with a polymer to increase the steric hindrance of the pigment. This can be one or more combinations of vinyl pyrrolidone, styrene, carboxy styrene, amino styrene, hydroxy acrylate, methacrylate, acrylate, etc.

[0035] (3) Modify the polymer chain with photosensitive reactive groups for subsequent photocuring reactions. These can be vinyl, acetylene and other functional groups that can undergo further cross-linking.

[0036] (4) The obtained modified pigment is mixed with solvent, monomer, additive, initiator, etc. to form a photoresist for standby use.

[0037] Example 1: (Pigment modification 1): (1) Modify the reaction site. First, use concentrated HI to hydroxylate the pigment surface, and then react with allyl bromide to modify the vinyl unsaturated group.

[0038] (2) Polymer coating. The polymer monomers include hydroxyethyl acrylate and isooctyl acrylate. Free radical polymerization is carried out under the catalysis of polymerization initiator AIBN to coat the pigment, thereby improving the dispersibility of the pigment in the solvent.

[0039] (3) Grafting of photosensitive groups. Compound 1 with photosensitive groups is obtained by reacting isophorone diisocyanate with hydroxy acrylate, and then compound 1 is grafted onto the pigment molecule to obtain G pigment with uniform positive charge (-NH-R dissociates in the solvent to be positively charged) and photosensitive groups. The specific preparation process is shown in Figures 1 (a) and 1 (b). The infrared spectrum is shown in Figures 1 (a) and 1 (b). Figure 3 Modified G color material: 3404 cm -1 For NH, 2942 cm -1 The CH stretching vibration absorption peak on the alkyl or cyclohexyl group is 1726 cm -1 is the stretching vibration absorption peak of the ester group, 1640 cm -1 is the stretching vibration absorption peak of C=C, 1508 cm -1 、1460 cm -1 is the vibration absorption peak of the benzene ring skeleton C=C, 1158 cm -1 It is the stretching vibration absorption peak of the ester group COC.

[0040] Example 2 (pigment modification 2): (1) Modify the reaction site. First, SiO2 is coated on the pigment surface, and then a silane coupling agent (such as KH570) is grafted.

[0041] (2) Polymer coating. The polymer monomers include hydroxyethyl acrylate, isooctyl acrylate, and p-carboxystyrene. Free radical polymerization is carried out under the catalysis of the polymerization initiator AIBN to coat the pigment, thereby improving the dispersibility of the pigment in the solvent.

[0042] (3) Grafting photosensitizing groups: Grafting the compound 1 with photosensitizing groups obtained in Example 1 onto the pigment molecules to obtain R pigment with uniform negative charge (-COOH dissociates in the solvent to be negatively charged) and photosensitizing groups. The specific preparation process is shown in Figures 2 (a) and 2 (b). The infrared spectrum is as follows: Figure 3 Modified R color material: 3399 cm -1 The NH or OH group stretching vibration absorption peak on the molecule, 2955 cm -1 、2933 cm -1 The CH stretching vibration absorption peak on the alkyl or cyclohexyl group is 1733 cm -1 is the stretching vibration absorption peak of C=O in the ester group, 1645cm -1 The stretching vibration absorption peaks of C=C are 1605 cm-1 and 1500 cm -1 、1449 cm -1 is the vibration absorption peak of the benzene ring skeleton C=C, 1147 cm -1 It is the stretching vibration absorption peak of the ester group COC.

[0043] Example 3 (Photoresist mixing): (1) Weigh 0.1~1wt% additive, 0.1~2wt% initiator, and 5~15wt% monomer respectively and dissolve them in 60~80wt% solvent, stirring to make the solution uniform; (2) Add 5-15wt% of modified pigment and stir at room temperature for 0.5-12h; (3) Filter to obtain the target photoresist.

[0044] Example 4 (Preparation of Color Resistant Layer on CF Substrate) Product manufacturing process, forming color resist layers of different colors one by one: (1) The three electrodes R, G, and B are pre-carved using mask lithography technology (the electrodes of a single color should be connected to facilitate later power-on). The schematic structure is as follows Figure 4 ; (2) A photoresist containing pigment particles with single positive (or negative) charge R, G, B and photosensitive groups is obtained by modification and mixing; (3) Apply R photoresist and apply power to the pre-lithographic R pattern position. A positive potential is applied to the R color block, and a negative potential is applied to the G and B color blocks. The applied voltage can range from 0.5 V / um to 5 V / um. The particle migration action can usually be completed within a few seconds or tens of seconds; (4) Then, the solvent is dried, the entire surface is exposed, and post-dried to obtain the R single-channel color resist layer.

[0045] (5) Repeat three times to obtain a full-color CF layer containing R, G, and B. The relevant results are shown in the following table.

[0046]

[0047] The above embodiment combines the particle electrophoresis principle with photoresist production to develop a photoresist with high selective electrodeposition. It can use a one-step electrodeposition curing method to accurately deposit the photoresist onto a pre-etched electrode pattern. This can provide a low-cost alternative solution for manufacturing high PPI color resists, with a minimum resolution of 2 μm, and has the advantages of high material utilization, saving photolithography process and green environmental protection, which is of great significance to the improvement of existing color resist processes.

[0048] Photoresist electrodeposition technology has huge technical advantages, but its implementation process is very difficult. One is that the surface charge of the particles and their response threshold to the electric field are difficult to control. The second is that the particles need to be fixed after one power-on (because photoresist is different from quantum dots, its pigment dispersibility and reliability in the liquid crystal panel need to be considered after curing). Therefore, how to solve the particle charge regulation and cure the deposited pigment particles has become a problem worth exploring. Based on this, this embodiment directly grafts a polymer material (dispersion resin) containing a charged group and a photosensitive reaction group onto the R, G, and B pigment molecules, so that the pigment particles have a single charge and are evenly dispersed in the solvent, thereby obtaining a corresponding color photoresist material, solving the curing problem after the electrodeposition photoresist is deposited.

[0049] Combined with the three electrodes R, G, and B that are pre-carved on the entire surface using mask lithography technology, the pigment particles in the power control system are deposited in a directional manner. Then the entire substrate is exposed to light, so that the photosensitive reaction groups on the pigment are cross-linked and cured. Finally, a cleaning process is performed to complete one or two color resist processes. Repeating one or two more processes can produce a full-color CF substrate (the areas without pigments cannot be cross-linked and cured due to the lack of pigments and photosensitive resins, and no color resist residue will be produced). The electro-deposited color resist layer produced in this way is not only size-controllable and high-resolution, but also greatly improves the color uniformity and reliability of the color resist layer.

[0050] The optional methods in the specific implementation process are as follows: ① Pigments include: Pigment Red 9, 19, 38, 43, 97, 122, 123, 144, 149, 166, 168, 177, 179, 180, 192, 208, 209, 215, 216, 217, 220, 223, 224, 226, 227, 228, 240, 252, 254, 255, 264, 270, 291. Among them, the most common pigments for photoresist are 177, 254, 291; Pigment Green 7, 36, 56, 58, 59, G dye (zinc phthalocyanine); Pigment Blue 15, 15:6, 16, 22, 23, 29, 60, 64; Pigment Green 7, 36, 56. Pigment Yellow 20, 23, 24, 86, 81, 83, 93, 108, 109, 110, 117, 125, 137, 138, 139, 147, 148, 150, 153, 154, 166, 168, 185, 231.

[0051] ② The unsaturated carboxylic acid used for pigment modification is selected from one or a combination of acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, vinyl benzoic acid, etc.; the unsaturated amine is selected from one or a combination of vinyl aniline, vinyl amine, etc.; the compound containing unsaturated olefinic bonds is selected from one or a combination of acrylate, methacrylate, styrene, α-methylstyrene, acrylonitrile.

[0052] ③ The solvent is usually a single polar solvent. The -COOH (-NH2) on the pigment polymer can be directly dissociated in the solution to promote particle charging. Most of them are ketones, ethers and ketone solvents with medium to high boiling points and low evaporation rates, such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, ethylene glycol dibutyl ether, ethylene glycol ethyl ether acetate, diethylene glycol ethyl ether acetate, diethylene glycol butyl ether acetate, propylene glycol monomethyl ether ester (PGMEA), cyclohexanone, isophorone, etc.

[0053] ④Monomer: Common polymerizable monomers (cross-linking agents) are acrylic esters of polyhydroxy alcohols.

[0054] ⑤ Initiator: including one or a mixture of more than one of 2,2-azobisisobutyronitrile, benzoin, benzophenone, anthraquinone, acetophenone and bisimidazole.

[0055] Option 2: Thermosensitive polymers (resins) are modified on the surface of pigment particles. The -COOH (or -NH2) and other groups on the polymer can be dissociated in polar solvents and charged. Then, the pigment is selectively deposited by applying electricity, so that the pigment can be deposited at the corresponding position. The thermosensitive reaction groups on the polymer can provide cross-linking sites for subsequent photocuring.

[0056] Similar to Scheme 1, the polymerizing group will undergo a curing reaction with the monomer in the solution. The difference is that the reaction type is a thermal curing reaction, and the initiation condition is not photo-initiation but thermal initiation.

[0057] For example, the thermal curing reaction is a thermal polymerization reaction of organic silicon, where the oxygen atoms in the multifunctional silane monomer replace the silicon atoms in the silicon-oxygen chain to form a silicon-oxygen-silicon bond. The result of the crosslinking reaction is a three-dimensional network structure of organic silicon resin. The degree of crosslinking depends on the molar ratio of the multifunctional silane monomer and the conditions of the crosslinking reaction. The more crosslinking, the higher the hardness and strength of the resin.

[0058] For another example, the heat curing reaction is epoxy thermal polymerization, and the heat-sensitive reactive group is an epoxy group, which can react with the monomer under thermal initiation conditions to undergo epoxy thermal polymerization. Although the epoxy group has extremely high reactivity, it is very stable if there is no curing agent, catalyst or harmful impurities. Under the catalysis of Lewis bases such as tertiary amines or Lewis acids such as boron trifluoride, the epoxy group of epoxy resin will open the ring and homopolymerize according to the ionic polymerization mechanism. If a tertiary amine is present, the epoxy group will open the ring according to the anionic polymerization process, causing the molecular chain to continue to grow or cross-link.

[0059] Optionally, the charge of the R, G, and B pigment particles in the above embodiment can be controlled by adjusting the monomers used during polymerization and the amounts thereof.

[0060] The modified pigment structures listed above are only partial representatives. Other color-blocking dispersions and related applications containing the same concept are all within the scope of protection of this patent.

[0061] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A color resist dispersion, characterized in that: It includes a polar solvent, a monomer dissolved in the polar solvent, and a modified pigment; The modified pigment is a pigment whose surface is modified and connected to a dispersing resin, wherein the dispersing resin has a charged group and a polymerizing group; the charged group dissociates and becomes charged in the polar solvent, and the polymerizing group and the monomer can undergo a cross-linking polymerization reaction under initiation conditions.

2. The color resist dispersion according to claim 1, characterized in that: The polar solvent is selected from one of diethylene glycol dimethyl ether, diethylene glycol diethyl ether, ethylene glycol dibutyl ether, ethylene glycol ethyl ether acetate, diethylene glycol ethyl ether acetate, diethylene glycol butyl ether acetate, propylene glycol monomethyl ether ester, cyclohexanone, and isophorone; The charged group is selected from at least one of -OH, -COOH, -NH2, and -NHR.

3. The color resist dispersion according to claim 1, characterized in that: The initiation condition is photo-initiation, and the photosensitive reaction group on the polymerizing group undergoes a photocuring reaction with the monomer.

4. The color resist dispersion according to claim 1, characterized in that: The initiation condition is thermal initiation, and the heat-sensitive reaction group on the polymerizing group undergoes a thermal curing reaction with the monomer.

5. The color resist dispersion according to claim 4, characterized in that: The heat-sensitive reactive group is a silicon-oxygen bond in a silicon-oxygen chain, and the silicon-oxygen bond can react with a silane monomer to undergo an organic silicon thermal polymerization reaction under heat-initiated conditions.

6. The color resist dispersion according to claim 4, characterized in that: The heat-sensitive reactive group is an epoxy group, which can undergo epoxy thermal polymerization reaction with the monomer under heat initiation conditions.

7. A method for preparing a color resist layer, characterized in that: The steps include: S1, the entire surface of R, G, and B electrodes are carved on the CF substrate using photolithography technology; S2. The color resist dispersion according to any one of claims 1 to 6, electrically controlled to allow the modified pigment to be directionally deposited on the three electrodes; S3. Under initiation conditions, the polymeric groups on the modified pigment undergo cross-linking polymerization with the monomers, and cross-linking and curing form a color resist layer.

8. The method for preparing a color resist layer according to claim 7, characterized in that: Electrodes of the same color are connected.

9. The method for preparing a color resist layer according to claim 7, characterized in that: The three colors of color resist dispersion liquid R, G, and B are used one by one to form color resist layers of corresponding colors respectively.

10. The method for preparing a color resist layer according to claim 9, characterized in that: After curing one color of color resist, clean it and then proceed to the color resist process of another color.

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